Police 'not bright enough' for spying

An attempt to shift the monitoring of communists and "other subversives" away from MI5 after the war was scotched because the police were considered not intelligent enough and potentially corrupt, according to a top secret file.

The first director general of MI5, Sir David Petrie, a former chief constable himself, insisted that spying required "the same mental equipment as you employ in the higher grades of the civil service".

A special breed of officers was needed, he wrote in 1945 to Sir Alexander Maxwell, the permanent under-secretary at the Home Office. He told Sir Alexander in a memo, released yesterday by the public record office, that ordinary PCs could "not always be expected to appreciate the need of complete secrecy".

He added: "There is also in the background the ugly question of corruption, on which I will say no more than ask you to cast your mind back to some of the material shown you... in the summer of 1943 and at subsequent periods."

The plan to shift responsibilities was raised by the Home Office as part of a stepping-down of domestic spying, which voters would stomach less easily once peace had resumed.

The proposals also hinted at combining MI5 and SIS, the department responsible for espionage overseas - an idea which caused concern among civil servants .

Sir David Petrie's memo included frank views about the threat of communism and his irritation with two chief constables who had raised objections to police "interfering in a political movement".